Apparatus for removal and destruction of ammonia from an aqueous medium

ABSTRACT

Methods and apparatuses are provided for the removal and destruction of ammonia from an aqueous medium. The methods and apparatuses include the removal of ammonia from an aqueous medium by contact with either natural or synthetic zeolite. The spent zeolite is re-generated for continuous use, while the ammonia is concentrated as ammonium sulfate, and ultimately destroyed via combustion. A system for monitoring and maintaining an ammonia removal system by an off-site provider is also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

The present non-provisional patent application claims priority to U.S. Provisional Application Ser. No. 60/325,141, filed on Sep. 26, 2001, entitled METHODS AND APPARATUS FOR REMOVAL AND DESTRUCTION OF AMMONIA FROM AN AQUEOUS MEDIUM USING ZEOLITES, which is herein incorporated by reference.

FIELD OF THE INVENTION

The invention generally relates to the removal and destruction of ammonia from aqueous media. More specifically, the invention provides systems, methods and apparatuses for the effective removal of ammonia from water as it is treated in a water treatment facility, and in particular, to systems, methods and apparatuses for the removal and destruction of ammonia from drinking water by contacting the water with zeolite materials.

BACKGROUND OF THE INVENTION

Cities and towns throughout the world depend on having clean potable water supplies. The dependence on clean water has increased as the population of the world has increased, especially as industrial use of rivers and lakes have become commonplace.

The explosion of world population, and corresponding increase in fresh water use, has resulted in a need to maximize water usage. However, the ability to maximize fresh water use has been limited by, (1) increased pollution of the fresh water supplies due to higher industrial output throughout the world (a direct result of the increased population); and (2) increased knowledge and standards for what constitutes clean water, acceptable for use in farming, industry, and consumption. As a result, there is a current need to increase the efficiency in the use of water, i.e., conserve existing clean water supplies, increase the current capabilities used to remove pollutants from water supplies, and increase the effectiveness of existing technologies and develop new technologies to effectively treat and reach new standards in water quality.

In this light, ammonia contamination of water resources has proven to be extremely problematic. High levels of ammonia commonly occur in wastewater, and occasionally drinking water, as a result of well contamination by industrial and agricultural processes. Presently, there is a trend to lower the ammonia discharge limits for facilities toward a range of 2 to 4 parts per million (ppm) from a previous ranges of 10 to 15 ppm.

Conventional ammonia removal technology has focused on additional aeration at wastewater treatment plant lagoons. In general, this remedy has proven ineffective. In contrast, a number of new technologies, focused on other wastewater related problems, have had the side-effect of lowering ammonia discharges. For example, activated sludge wastewater plants are being constructed to eliminate a full range of biological contaminants and have the added benefit of decreased ammonia discharges to 2 ppm or less. These plants however are expensive and not required in areas where the only problem is high ammonia levels. Further, technologies such as Sequence Batch Reactors (SBR's), Rotating Biological Filters (RBF's), and Trickle Filters are also used to solve non-ammonia related wastewater cleanup problems, but ammonia reduction seems to be an added benefit. However, these newer technological options require entirely new facilities or expensive rebuilds at existing facilities. This is an appropriate response where a wastewater problem is significant and requires a fairly drastic improvement. However, facilities with efficiently operating wastewater plants need options that are relatively inexpensive, compared to rebuilding the entire facility, and focused on lowering the ammonia discharge levels, not on other, typically more expensive, cleanup problems. Against this backdrop the present invention has been developed.

BRIEF SUMMARY OF THE INVENTION

The present invention provides systems, methods and apparatuses for the removal and destruction of ammonia from an aqueous medium using zeolite materials. The zeolite materials of the present invention absorb ammonia at levels sufficient to comply with discharge limits set by the EPA. Spent zeolite is re-freshed and re-used, where the ammonia on the zeolite is stripped and concentrated as an ammonium salt. Stored ammonium salts are used in the manufacture of fertilizers, or simply converted to a form for combustion, and release as nitrogen into the atmosphere.

The present invention also provides methods and apparatus for operating an ammonia removal and destruction facility, in accordance with the present invention, from an off-site location. The system includes providing a pre-determined amount of zeolite for removal of ammonia from the target water source, providing and maintaining the required chemical compounds for the storage or destruction of the ammonia, and operation and maintenance of a combustion unit for conversion of the ammonium to a nitrogen containing gas for release into the atmosphere.

These and various other features as well as advantages which characterize the invention will be apparent from a reading of the following detailed description and a review of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic for the removal and destruction of ammonia in accordance with an embodiment of the present invention.

FIG. 2 illustrates a schematic for the ammonia absorption process in accordance with an embodiment of the present invention.

FIG. 3 illustrates a schematic for the combustion of ammonia in accordance with an embodiment of the present invention.

FIG. 4 illustrates a schematic of the overall removal and destruction of ammonia in accordance with an embodiment of the present invention.

FIGS. 5A, A2, B, B2, C1 and C2 provide a theoretical mass balance calculation for the schematic shown in FIG. 4.

FIG. 6 is graphical representation of bed volume against concentration for the data illustrated in Tables 6 and 7.

FIGS. 7A–H illustrate tabular and graphical data involved in a five column run in accordance with an embodiment of the present invention.

FIGS. 8A–F illustrate tabular and graphical data involved in another five column run in accordance with an embodiment of the present invention.

FIGS. 9A–F illustrate tabular and graphical data involved in another five column run in accordance with an embodiment of the present invention.

FIGS. 10A–F illustrate tabular and graphical data involved in another five column run in accordance with an embodiment of the present invention.

FIG. 11 provides data from a pilot study performed at Colorado City, Colo., showing the feed and discharge levels of ammonia for a 1000 gallon treatment in accordance with embodiments of the present invention.

FIG. 12 is a schematic of the air stripping process in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Definitions:

The following definitions are provided to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure.

“Aqueous medium” refers to water or any liquid made from, with, or by water.

“Feed” refers to an aqueous medium before treatment with the systems and methods of the present invention, for example, a flowing water source before it enters a wastewater treatment facility.

“Zeolite” refers to a natural and/or synthetic zeolite. Natural zeolites are hydrated silicates of aluminum and either sodium or calcium or both, for example clinoptilolite and chabazite. Synthetic zeolites are made by a number of well known processes, for example gel or clay processes, which form a matrix to which the zeolite is added. Example synthetic zeolites include Linde® AW-30 and Zeolon® 900.

“bed volume” for a particular housing member refers to the volume of zeolite in the housing member. The term bed volume, for purposes of the present invention, also refers to the retention volume and/or specific retention volume. Note that bed volume has units of liters, cubic meters, or cubic feet.

“Remove” refers to the detectable decrease of a target material, for example ammonia, from a source, for example ground water. Typically removal of arsenic from an aqueous source is at least 50%, preferably at least 75% and most preferably at least 90%, from the original levels in the zeolite treated source.

“Absorb” and “adsorb” refer to the same basic principle of one substance being retained by another substance. The processes can include attraction of one substance to the surface of another substance or the penetration of one substance into the inner structure of another substance. The present invention contemplates that zeolite can either absorb and/or adsorb ammonia from an aqueous medium and that for purposes of the present invention, that the two principles be interchangeable. Other terms used to describe this interaction include binding or trapping, each of which contemplates absorption and/or adsorption. As used in the present invention, the term absorb refers to any or all of adsorb, trap, bind, and the like.

Zeolite:

Zeolites, in accordance with the present invention, effectively absorb, adsorb, bind and/or trap ammonia in an aqueous media, and thereby remove it from the aqueous media. Compositionally, zeolites are similar to clay minerals, where zeolites are natural hydrated silicates of aluminum and either sodium or calcium or both. Unlike clays, which have a layered crystalline structure (similar to a deck of cards that is subject to shrinking and swelling as water is absorbed), zeolites have a rigid three-dimensional crystalline structure. Zeolites' rigid honeycomb-like crystalline structure consists of a network of interconnected tunnels and cages, thereby forming a series of substantially uniformly sized pores. Aqueous media moves freely in and out of the pores formed by the crystalline structure, making zeolite an excellent sieving or filtration type material, as well as providing a large surface area for binding ammonia within the target aqueous medium. Zeolite is host to water molecules and ions or potassium, sodium, and calcium, as well as a variety of other positively charged ions, but only those of appropriate molecular size fit into the pores, creating the “sieving” property.

There are approximately fifty different types of natural zeolites, including clinoptilolite, chabazite, phillipsite, mordenite, analcite, heulandite, stilbite, thomosonite, brewsterite, wellsite, harmotome, leonhardite, eschellite, erionite, epidesmine, and the like. Differences between the different zeolites include particle density, cation selectivity, molecular pore size, and cation affinity. For example, clinoptilolite, the most common natural zeolite, has 16% more void volume and pores as much as 0.2 nm larger than analcime, another common zeolite.

Preferable natural zeolites for use in the present invention include any zeolite having an exchange capacity with sufficient capacity to lower the ammonia concentration in an aqueous medium from a first level to a second level. Preferable zeolites for use in the present invention have a capacity for ammonia of at least 1 meq/gram, although other lower capacity zeolites are envisioned to be within the scope of the present invention. In addition, zeolites having particle sizes from 10×60 mesh and preferably 20×40 mesh are useful in the present invention. Zeolite fines are typically removed before use in the present invention to prevent plugging in the tanks of the present invention (see below). Preferable natural zeolites for use in the present invention include clinoptilolite.

Table 1 provides a list of companies that presently produce zeolite minerals in either the United States or Canada. Table 1 provides a chemical analysis of the zeolite materials sold by a number of companies, and provides the physical properties of the corresponding zeolite materials. This Table is provided as illustrative of the type of zeolite material that can be purchased for large scale use.

TABLE 1 Chemical Analysis (Expressed in Weight %) Company Location Na₂O K₂O CaO MgO SiO₂ Al₂O₃ TiO₂ Fe₂O₃ Addwest Minerals WY 4.7 1.9 1.6 0.65 74.0 14.0 0.1 2.1 American Research NV/CA 3.5 3.8 0.7 0.4 69.1 11.9 — 0.74 Am. Absorbents OR 0.8 3.8 0.7 0.4 69.1 11.9 0.2 0.7 Stellhead Res. CA/NM/OR 0.8 3.8 0.7 0.4 69.1 11.9 0.2 0.4 Teague Minerals OR 0.9 4.7 1.4 0.3 64.1 11.8 0.3 2.58 Zeotech TX 0.6 1.7 2.4 0.7 68.4 12.1 NK NK St. Cloud Mining NM 0.9 3.3 3.3 1.0 64.7 12.6 0.2 1.8 W-Way Zeolites Canada 2.5 2.7 3.4 1.3 65.8 14.3 0.3 2.6 Highwood Res Canada 2.78 2.79 3.78 0.95 64.5 13.7 0.27 2.19 C2C Mining Canada 1.35 1.57 2.51 1.55 66.8 11.2 0.6 5.2 Physical Properties Ionic Exch H₂O % Free Silica pH Pore Company Cap (meq/g) Adsorption (%) SG Color (nat.) Diam. (Å) Hard. Addwest Minerals 2.00 14.0 2.00 1.5 pale blue 4.4 3.7 American Research 1.85 12.3 NK NK 4.0 5.1 Am. Absorbents 1.4 1.50 2.3 white 8.0 4.0 3.8 Stellhead Res. 1.30 0.09 1.6 white 8.0 4.0 5.1 Teague Minerals 1.77 low 2.2 off white not not provided provided Zeotech St. Cloud Mining 1.60   0.01< 2.3 white 8.0 4.0 3.8 W-Way Zeolies 1.00 25.0 NK 2.4 off white/ 8.1 6.5 NK pale green Highwood Res 1.00 10.0  2.0 7.0 C2C Mining NK NK 5.00 2.3 brown 5.0 NK NK

It is also envisioned that synthetic zeolites can be used in accordance with the present invention. Synthetic zeolites are made by well known processes, such as a gel process (sodium silicate and alumina) or clay process (kaolin), which form a matrix to which the zeolite is added. Preferable synthetic zeolites include Linde®AW-30, Linde®AW-500, Linde®4-A and Zeolon®900.

It is envisioned that the systems and methods of the present invention can utilize either natural, synthetic or a mixture of natural and synthetic zeolite in the removal of ammonia from aqueous medium.

Ammonia Removal from Aqueous Medium Using Zeolite

Ammonia Absorption:

The absorption of ammonia from an aqueous medium is effected by causing contact between the aqueous medium and zeolite. During the contact period, ammonia in the aqueous medium absorbs onto the zeolite and is effectively removed from the aqueous medium. The zeolite at this point is considered “loaded” with ammonia.

There are two series of chemical reactions believed to occur in the absorption of ammonia to the zeolite. The first series of reactions occurs when the fresh zeolite is initially loaded into an absorption column (see below). The second series of reactions occurs after the zeolite has been migrated through the absorption process, including the elution step. The initial reactions result from the fact that natural zeolite is loaded with sodium ions, the second series of reactions results from the addition of alkaline (basic) material to the system. The alkaline material can be calcium oxide, “calcium based,” sodium hydroxide, “sodium-based,” or potassium hydroxide, “potassium based.” It is envisioned that other alkaline metals could be used in this context, for example, lithium, rubidium and cesium, but all are less preferable due to economic reasons. The two series of reactions are shown below with regard to a “calcium-based” system:

Initial Loading on Zeolite: Ca⁺⁺+NaZeol→2Na⁺+CaZeol 2NH₄ ⁺+Na₂Zeol→2Na⁺(NH₄)₂Zeol 2K⁺+Na₂Zeol→2Na⁺+K₂Zeol Equilibrium Loading on Zeolite: 2NH₄ ⁺+Ca₂Zeol→Ca⁺⁺+(NH₄)₂Zeol 2K⁺+Ca₂Zeol→Ca⁺⁺+K₂Zeol Ammonia Elution:

The ammonia, once loaded onto the zeolite, is passed from the absorption process to an elution unit process. The elution unit process (see below) functions to remove the ammonia absorbed to the zeolite. This is generally accomplished by contacting the loaded zeolite with a salt solution, or brine. The brine is typically composed of sodium, calcium, potassium, and/or magnesium ions in solution. The contact between the loaded zeolite and the brine causes ion displacement between the salt ions and the ammonia, thereby removing the ammonia from the zeolite and creating a “pregnant” brine solution relative to the concentration of ammonia. The chemical reactions of the elution step are illustrated below: (NH₄)₂Zeol+Ca⁺⁺→2NH₄ ⁺+Ca₂Zeol K₂Zeol+Ca⁺⁺→2K⁺Ca₂Zeol

The elution step is in effect the reversal of the reactions discussed with respect to the absorption step above and is driven by the high concentration of salt ions in the brine solution relative to the concentration of ammonia.

Ammonia Dissociation from Brine:

The pregnant brine is fed to an air stripping unit process where the ammonia is dissociated from the brine. Generally, the pH in the pregnant brine is increased to a range of approximately 10 to 11 prior to contact with the air to facilitate the stripping process. In a preferred embodiment of the present invention, the pH is increased by the addition of lime to the brine. The lime helps to dissociate the ammonia from the brine in the form of ammonium hydroxide.

In the air stripping process, contact between air bubbles and loaded brine cause the diffusion of the ammonia from the brine to the air in the form of ammonia gas. The ammonia dissociation reaction steps that occur in the air stripping process are as follows: 2NH₄ ⁺+2Cl⁻+CaO+H₂O→CaCl₂+2NH₄OH 2NH₄OH→2NH₃+2H₂O

The air/ammonia mixture is then transferred to an air scrubbing step.

Acid Wash to form Ammonium Salt:

The air/ammonia mixture is treated with an acid wash to form an ammonium salt. Preferably, the air is treated with a sulfuric acid (H₂SO₄), or other like acid, wash via the following reaction: 2NH₃+H₂SO₄→(NH₄)₂SO₄

Note that the air can preferably be re-circulated in the air stripper.

Storage and Destruction of Ammonium Salt

The ammonium sulfate is passed to a storage tank, or to a re-circulation tank, for ultimate disposal. Ammonium sulfate, in one embodiment of the present invention, is removed from the storage tank and supplied for use in fertilizer and other commercial purpose. However, it has been determined that disposal through these uses can be of marginal economic advantage due to the relatively low concentration of the ammonium sulfate. As such, other embodiments of the present invention are envisioned for the disposal of the ammonium salt, preferably via the destruction of the ammonia through combustion.

Combustion of Ammonia:

The ammonium sulfate in the storage tank is mixed with a basic material, such as lime or other like agent, and passed to an air stripping unit similar to the one described above. The ammonium sulfate stream is reacted with lime to dissociate the ammonia in the form of ammonium hydroxide and facilitate air stripping. The ammonium hydroxide is then removed from the solution as ammonia gas by contacting the solution with a flow of air. The ammonia gas is passed to a combustion unit to be burned at a controlled temperature to avoid the production of NO_(x) gases.

Typically, the combustion unit is heated by natural gas and includes various streams available to vary the composition of the ammonia gas mixture for ideal combustion. For example, where the concentration of the ammonia gas in air is too high, e.g., greater than 1.1% by weight ammonia in the gas stream, the ammonia gas stream is diluted with air. Where the concentration of the ammonia in the air is too low, e.g., less than 1.1% by weight ammonia in the gas stream, the ammonia gas stream is combined with a combustion gas supply to facilitate combustion (increasing the temperature of the stream).

If required, the combustion air supply can be a mixture of burner gas and air that is burned in a pre-burner prior to entering the combustion chamber of the present invention. The exhaust gas from the pre-burner is fed to the combustion unit to raise the temperature of the combustion step to the required level, i.e., the temperature required to combust the concentration of ammonia gas in the gas stream.

Preferably, the concentration of ammonium sulfate fed to the destruction process is in the range of about 20% to about 40% by volume. If the ammonium sulfate is not at this concentration, it is fed to a recirculation tank where the ammonium sulfate is re-circulated through the acid scrubbing process and bled in increments to the destruction process (when the appropriate concentration is reached). The following chemical reactions are believed to occur during the combustion unit process: (NH₄)₂SO₄+CaO+3H₂O→2NH₄OH+CaSO₄H₂O 2NH₄OH→2NH₃+2H₂O CH₄ ⁺+4NH₃+3O₂+N₂→8H₂O+N₂+CO₂ Zeolite Flow:

The zeolite for use in the present invention is input into the process at the ammonia absorption step. Typically an appropriate amount of zeolite is charged into a housing member(s), e.g., tank, column, etc, for contact with the aqueous medium. The zeolite is maintained within the absorption step and contacted with the aqueous medium for an amount of time sufficient to decrease the concentration of ammonia from a first level (in the feed of the aqueous medium) to a second level (in the discharge of the aqueous medium). In preferred embodiments the discharge level is less than the acceptable discharge limits for ammonia as set by the Environmental Protection Agency (EPA).

Loaded zeolite passes from the absorption step to the stripping unit process (see above), where the ammonia is eluted from the zeolite. The zeolite is passed from the elution process to a rinse unit where the zeolite is cleaned for re-circulation back to the absorption step. In the rinse step, the zeolite stream is fed to a rinse column where it is rinsed with water. Note that the rinse step can include a reverse osmosis unit where chemicals contained in the rinse stream, including calcium, chloride, sulfate, hydroxide, and carbonate are recovered. The recovery of these chemicals helps defray the overall operation costs, as the chemicals can be re-used. Note also that the reverse osmosis unit lowers the pH and total dissolved solids (TDS) content of the discharge stream.

Once refreshed/regenerated, the zeolite is pumped back to the absorption step and the absorption process repeated. It is believed that the zeolite can be re-used in this manner for an indefinite period of time. However, degradation of the zeolite does occur over time, and degraded zeolite is removed or purged from the system by passing it through with the discharge stream. As such, a fairly predictable amount of zeolite must be added to the absorption process to keep a fairly constant amount of zeolite in the system (typically equal to the amount of degraded zeolite purged from the system).

Embodiments of the present invention will now be described with reference to the following Figures.

FIG. 1 provides a process diagram or schematic 100 of ammonia removal and destruction in accordance with the present invention. Aqueous medium 102 is feed into the absorption step 104 (ion exchange). The ammonia is removed from the aqueous medium, which is discharged having a discharge level of ammonia 106. The ammonia loaded zeolite is next treated with brine in an elution step 108 to release ammonia. The zeolite is recovered in a rinse step 110 and cleaned for re-use in the absorption step (as shown by line 112). The ammonia/brine solution is treated with an air strip step 114 and an acid scrubbing step 116 as described above, for ultimate storage 118 and use, or storage/re-circulation to increase the ammonia concentration for ultimate destruction 120.

FIG. 2 is a schematic diagram 200 of an absorption unit process according to one embodiment of the present invention. In this embodiment, three absorption columns 202, 204, and 206 are provided for contact between the zeolite and aqueous medium. The aqueous medium 208 is fed up-flow through the first absorption column 202, into the second absorption column 204, and into a third absorption column 206, and then discharged from the system 210. The absorption columns can be operated as fixed bed, fluidized bed, or as stirred reactors. Most preferably, the columns are operated as fluidized bed.

The aqueous medium 208 is fed to the absorption tanks at a flow rate such that the zeolite (generally in the form of a slurry) is fluidized in the columns. For example, it has been determined that an aqueous medium having an up-flow rate of 10 gal/ft² is sufficient to fluidize a bed of zeolite comprising 20×40 mesh zeolite, resulting in between a 40% and 45% expansion of the zeolite. The up-flow configuration creating a fluidized bed is preferred because there is a decreased likelihood of bio-fouling of the columns, the equipment tends not to short-circuit as often, and the configuration allows the degraded zeolite to be discharged from the system with the aqueous medium.

In one particular embodiment of the present invention, the zeolite is migrated through the absorption process in a counter-current flow configuration 212 (see FIGS. 2 and 4). Here the aqueous medium with the strongest concentration of ammonia contacts zeolite that is already partially loaded, and fresh or stripped zeolite contacts the aqueous medium at a point where the concentration of ammonia is decreased. The configuration creates favorable conditions for obtaining a low ammonia content in the discharge and efficient loading of the ammonia on the zeolite.

Referring again to FIG. 2, the zeolite is passed from an elution step 214 to a rinse step 216, where the zeolite is rinsed clean with water or other like solution. The migration of the zeolite is accomplished through methods such as air-lifting or by positive displacement pumps. Air lifts are generally known technology which use compressed air to raise the zeolite in the absorption column by introducing compressed air into the zeolite near the bottom of the absorption column. The air mixes with the fluidized zeolite near the bottom of the column and causes the overall level of zeolite to rise thereby spilling over the top of the column, where the zeolite is collected and fed to the next column. In this manner the zeolite is continuously being transferred from column to column to column to rinse step back to the first column again. Note that the number of absorption columns can be varied with regard to the present invention, and is dependent on the capacity required by the overall system.

FIG. 3 provides a schematic diagram 300 of the destruction process in accordance with one embodiment of the present invention. In this embodiment, the storage tank 302 housing the ammonium sulfate feeds a stream of material (see line 304) to the ammonia recovery step 306, where an ammonia gas is fed 308 to a combustion 310 unit for destruction of the ammonia. In preferred embodiments, a pre-burner 312 is provided to ensure that lower concentrations of ammonia gas can be destroyed. Note also the lime storage tank 314 for ammonia recovery.

Referring to FIG. 4, a process diagram is shown of a preferred embodiment where four absorption columns 402 operating as fluidized beds and having the zeolite migrated counter-current to the flow of aqueous medium is shown. Note that a brine elution step and a rinse step, with a reverse osmosis unit, are provided to reclaim or recover useful chemicals (see below for additional detail). A destruction unit process, comprising an air stripping unit process and a combustion unit process, are also shown. Also note that the ammonium sulfate is stored in a re-circulation tank.

In more detail, the absorption columns 402 are charged with zeolite, preferably a natural zeolite, more preferably clinoptilolite, for contact with an aqueous medium. The aqueous medium feed 404, having a first level of ammonia, is pumped up-flow, via pump 406, to the first absorption tank at a sufficient flow rate to fluidize the zeolite (target of 40% to 45% expansion). The aqueous medium is then pumped from the first column through the remaining columns in an up-flow configuration utilizing pumps 408. As in column one, the flow rate should be sufficient to fluidize the zeolite in the remaining columns. The aqueous medium, now having a second level of ammonia, is discharged from the system as a discharge stream 410. The second level or discharge level of ammonia is preferably below the acceptable discharge limits as set by the EPA and is most preferably at a concentration of less than 1 mg/L.

The zeolite in the absorption system is pumped in a counter-current configuration to the flow of the aqueous medium. The fresh zeolite stream 412 enters the fourth absorption column first, by passing through a screen 414 provided for the conservation of material and minimization of TDS in the discharge. The zeolite in the absorption columns migrates from column four, to column three, to column two, to column one, and then to the elution step. Preferably, the zeolite is moved using air lifts, which are generally known in the art. The rate of migration is selected such that the contacting time with the aqueous medium is sufficient to produce an aqueous medium having a concentration of ammonia (second level) in the discharge stream 410 lower than the discharge limits set by the EPA. The zeolite stream exiting the first absorption tank is loaded with ammonia and becomes the loaded zeolite stream 416 fed to the elution column 418.

In the elution step, the loaded zeolite stream 416 is contacted in an elution column 418 with a lime input stream 420 and an eluant stream 422. The amount of lime, as stored in a lime storage tank 424, added to the elution column is determined such that the alkalinity of the brine solution is sufficient to remove nearly 100% of the ammonia from the loaded zeolite (this goes for the amount of time as well). The stripped zeolite exits the elution column, passes through a screen 426, and becomes the stripped zeolite feed 428 for the rinse process. The pregnant brine, or eluant stream 430, is fed to the air stripping unit 432.

With regard to the zeolite rinse process, the stripped zeolite stream 428 is rinsed with a rinse stream 434 in a rinse column 436. The rinse process may or may not include a reverse osmosis unit 438 depending on the discharge limits of various chemicals (if the discharge limits are low, it may be a requirement to install a reverse osmosis unit), such as chloride, and on the economic feasibility to recovering the chemicals.

The rinse stream 434 is preferably comprised of a water stream 440 and a reverse osmosis unit permeate 442. The reverse osmosis permeate 442 is created by the passage of the rinse stream 434 exiting the rinse column 436 through a reverse osmosis unit 438. The reverse osmosis concentrate 444 generally contains recovered chemicals such as calcium, chloride, sulfate, and carbonate, and is fed back into the elution column 418.

The zeolite stream exiting 428 the rinse column 436 is fed back to the fourth absorption column as regenerated zeolite 412. A difference between the stripped zeolite and newly loaded zeolite loaded into the columns 402 is that the regenerated zeolite has calcium ions absorbed thereto as opposed to sodium ions.

Referring again to the air stripping unit, a slurry containing the pregnant eluant 430 is mixed with lime 420 to a stripping column 432. An air feed stream 446 is added to the stripping column to facilitate the removal of the ammonia from the slurry 430, thereby creating a mixture of air and ammonia gas.

The air/ammonia mixture stream 448 is fed from the stripping column 432 to an air scrubbing unit 450 where it is washed with a scrubbing acid stream 452. The scrubbing acid stream 452 is created by an acid stream 454 mixed with an amount of product scrub stream 456 from the re-circulation tank 458. The scrubbing acid is preferably H₂SO₄ stored in a acid storage tank 460. Note that the scrubbing acid removes ammonia from the air/ammonia mixture and creates an ammonium sulfate solution. The ammonium sulfate solution is removed from the air scrubbing column 450 as the product scrub stream 456 and is transferred to the re-circulating tank 458. The scrubbing stream 452 contains an amount of the product scrub stream 456 as recycle. This recycle, coupled with the low percentage bleed of the product scrub stream 456 acts as a concentrator of ammonium sulfate. The concentration of this stream is a factor in the efficient combustion of the ammonia in the destruction process.

The ammonium sulfate in the re-circulating tank 458 is bled to a mixing tank 462 via stream line 464 for destruction. The amount of ammonium sulfate bled through line 464 is preferably less than 20% of the flow rate circulating between the re-circulation tank 458 and the air scrubber unit process. The ammonium sulfate solution is mixed in the mixing tank 462 with an amount of alkaline material, preferably lime, present in steam 466. The lime or other alkaline material is stored in alkaline storage tank 468. The lime is added to the ammonium sulfate to dissociate the ammonia from the hydroxide. This reaction also produces calcium sulfate (CaSO₄), or gypsum, which is preferably removed by passing the product through a filter (not shown).

In certain applications, where the gypsum in the mixing tank becomes very thick in consistency, dilution water 470 may be added. The filter separates out a gypsum cake from a filtrate 472 comprising ammonium hydroxide. The filtrate 472 is fed to an additional air stripping column 474 where it is contacted with an air stream 476 thereby removing the ammonia from the filtrate 472. The remaining liquid stream contains a relatively low concentration of remaining ammonia and can be bled from the air stripper back to the feed stream 404 (see line 478), or other low or non-ammonia containing waste disposal tank (not shown).

The ammonia containing air stream 480 exiting the air stripping column 474 is passed to a combustion unit 482. Depending on the concentration in the air stream, a dilution air stream 484 (to reduce combustion temperature) or a combustion air stream 486 (to increase combustion temperature) can be added to the combustion unit to facilitate combustion of the ammonia. The combustion air stream is blended with a methane stream 488 and passed to a pre-bumer (not shown) if necessary. The combustion reaction produces water vapor, nitrogen, and carbon dioxide. The products 490 of the combustion reaction are discharged into the atmosphere.

An alternative of the combustion air stream is to use a catalytic combustion device, for example, catalyst sold by CSM Worldwide, Inc., located at 200 Sheffield St., Mountainside, N.J. 07092. The catalyst would be used to facilitate the combustion of the ammonia in the combustion chamber.

FIGS. 5A, A2, B, B2, C1 and C2 show a theoretical mass balance calculation for the process schematic discussed in FIG. 4. The process requirements including flow rates, concentrations of streams, size of columns, and any other process conditions as were determined through the experimental procedures discussed in detail in the Examples which follow. Specifically, the test results shown in the Examples below were used to estimate the design process condition and assumption based in FIGS. 5A–C2. Additionally, several assumptions were made with respect to process conditions, for example, a theoretical one million gallon per day facility was used as the target facility.

Systems for Monitoring and Disposing of Ammonia From an Aqueous Medium

The present invention contemplates a system for operating the equipment required to remove ammonia from a target water source by an off-site provider, for example a company that specifically installs, monitors, trouble-shoots, and replaces the zeolite materials in the tanks/columns of the present invention. The off-site provider is contemplated to be hired by a municipality (or other like governmental or private water board) to maintain the ammonia levels in the municipalities water via the systems and methods of the present invention. The off-site provider is responsible for determining the ammonia removal requirements of the target water source, for example a water treatment facility, including the type and amount of zeolite required, the number of tanks necessary to house the zeolite, the design of the flow through the tanks, i.e., up-flow, down-flow or batch, the flow rate of the aqueous medium, the length of time before replacement of zeolite, the chemical components and amounts required for efficient removal and destruction of the ammonia, and the combustion requirements of the ammonia removal system, etc.

The off-site provider installs the properly charged zeolite materials at the water treatment facility and monitors the first level, second level, discharge level, etc of the ammonia in the water, and of the ammonia levels during the combustion process (note that the ammonia may be stored as an ammonium salt, which may also be controlled by the off-site provider). The ammonia monitoring can be technician based, i.e., a technician goes to the installed system and takes a sample for analysis, or can be performed by a pre-programmed monitoring unit that removes and analyzes a sample, and transmits the ammonia levels to an off-site monitoring unit, for example a computer via a wireless communication unit. The off-site monitoring unit can be equipped with a signaling means for alerting the off-site provider of over target ammonia levels for discharge, as well as for the levels of the zeolite in the system and the concentration of ammonia gas for combustion in the combustion unit. In one embodiment, the off-site provider has the capability of adding fresh zeolite to the absorption tanks when it is evident that the capacity of the system is insufficient for removing the requisite amount of ammonia.

The off-site provider is responsible for coordinating any maintenance or trouble-shooting issues that arise during the ammonia removal and destruction process. As such, alarms or other signaling devices may be included in the zeolite housing members or other units (air stripping, scrubbing, etc) to alert the provider of a potential malfunction in the system. Further, the off-site manager is responsible for the replacement of degraded zeolite.

The off-site provider installs the properly charged zeolite materials at the water treatment facility and monitors the first level, second level, discharge level, etc of the ammonia in the water, and of the concentration and chemical form of the ammonia during the storage and/or destruction process. As noted above, the ammonia monitoring can be technician based, i.e., a technician goes to the installed system and takes samples for analysis, or can be performed by a pre-programmed device that incrementally removes samples for analysis of ammonia levels, data being transmitted automatically to an off-site monitoring unit, for example a computer. The off-site monitoring unit can be equipped with a signaling means for alerting the off-site provider of over target ammonium levels for the discharge level, as well as for ammonium levels that are problematic during the combustion process, so that modifications can be made where appropriate.

The off-site provider is responsible for coordinating any maintenance or trouble-shooting issues that arise during the ammonia removal process, including the ordering and delivery of appropriate chemicals, for example lime, H₂SO₄, brine, etc. As such, alarms or other signaling devices may be included in the chemical component storage vessels, stream lines, etc, to alert the provider of a potential malfunction or shortcoming in the chemical storage or delivery.

As such, an off-site provider of the present invention can be hired by a third party (municipal water board, private water rights holder, etc.) to independently operate the ammonia removal and destruction system disclosed herein. In one embodiment, the off-site provider is an independent contractor specializing in the systems and methods of the present invention. In preferred embodiments, the off-site provider operates a plurality of ammonia removal and destruction systems at a number of geographically different sites for a number of different third parties.

In another embodiment, the off-site provider compiles data from its different sites to optimize the removal of ammonia and destruction of ammonia at those sites, i.e., data is compiled and compared, and optimized systems and methods developed. The data includes the basic parameters for operating the different embodiments of the invention, amounts of zeolite, flow rate concentration of brine, etc.

Finally, the systems and methods of the present invention provide business advantages for an off-site provider to remove and destroy ammonia from public or private water supplies, as managed by other third parties. The business methods provide economic and technological advantages to the third party for removing and destroying ammonia, as described by the embodiments of the present invention.

Having generally described the invention, the same will be more readily understood by reference to the following examples, which are provided by way of illustration and are not intended as limiting.

EXAMPLES Example 1 Sodium Zeolite Absorption of De-mineralized Water/Ammonia Feed

Tables 2 and 3 show the results of ammonia absorption from an aqueous medium by two columns connected in series charged with regenerated sodium chloride zeolite. The feed solution was prepared using de-mineralized water and adding approximately 28 mg/L ammonia thereto. The feed solution was pumped in an up-flow configuration at a flow rate of approximately 1.5 liters per min (L/min).

The data shown in Table 2 shows that the concentration of ammonia in the effluent of column one began at 0.06 mg/L and concluded at 20.6 mg/L. The effluent exiting column two began at 0.03 mg/L and remained below the discharge level (1 mg/L ammonia) for about 450 minutes. At the completion of the test, the ammonia concentration in the effluent of column 2 was 8.1 mg/L. These results suggest that at the selected flow rate, an additional column of charged zeolite is necessary to ensure that the ammonia concentration in the effluent or discharge stream is at a level lower than the standard discharge level as set by the EPA (approximately 1 mg/L).

TABLE 2 Ammonia removal from two columns connected in series Col. 1 Effluent Col. 2 Effluent Flow Bed Feed NH₃ meq meq NH₃ meq meq on % Time rate Vol. NH₃ meq NH₃ mg/L dischar. on zeol. mg/L disch. zeol. rec. 0 1.5 0 28.5 0 0.06 0 0 0.03 0 0 10 1.5 6 28.5 30.54 0.06 0.064 30.47 0.03 0.03 0.03 99.9 105 1.5 63 27.2 307.39 0.83 8.51 298.88 0.12 1.25 7.26 99.6 265 1.5 159 23.1 703.39 5.9 109.66 593.74 0.14 3.65 106.00 99.5 435 1.5 261 24.4 1147.82 10.5 300.91 846.92 0.77 17.68 283.23 98.5 450 1.8 324 18.2 1182.92 5.2 310.93 871.99 0.41 18.47 292.46 98.4 560 1.8 403.2 27.9 1577.51 15.8 534.39 1043.12 1.24 36.01 498.38 97.7 680 1.8 489.6 27.4 2000.25 19.7 838.33 1161. 3.38 88.16 750.18 95.6 800 1.8 576 28 2432.25 20.6 1156.2 1276.1 8.1 213.13 943.04 91.2

Table 3 summarizes the test data with regard to bed volumes and meq/g for columns one and two:

TABLE 3 Ammonia Concentration For Columns One and Two Bed Volume meq/g for Col. 1 meq/g for Col. 2 0 0.0 0.0 6 0.018 0.0 63 0.173 0.004 159 0.343 0.059 261 0.490 0.158 324 0.504 0.163 403 0.603 0.278 490 0.672 0.418 576 0.738 0.525

A second test was performed using similar parameters, except that the flow rate for the aqueous medium was 1.7 L/min and the initial concentration of ammonia in the feed was 37.4 mg/L. Again the results, as shown in Tables 4 and 5, were similar to the data in Tables 2 and 3, where the concentration of ammonia in the effluent at the end of the test exceeded the discharge limit of 1 mg/L (suggesting a third column would be desirable). However, as above, the data indicates the utility of zeolite in removing ammonia from an aqueous medium.

TABLE 4 Ammonia removal from two columns connected in series (1.7 L/min flow rate) Col. 1 Effluent Col. 2 Effluent Flow Bed Feed meq NH₃ meq meq on NH₃ meq meq on % Time rate Vol. NH₃ NH₃ mg/L dischar. zeol. mg/L dischar. zeol. rec. 0 1.7 0 37.4 0 1.19 0 0 2.54 0 0 0 20 1.7 13.6 37.4 90.83 1.19 2.89 87.94 2.54 6.17 −3.2 93.2 85 1.7 57.8 35.9 374.18 1.1 11.57 362.61 0.37 9.09 2.48 97.6 145 1.7 98.6 36.2 637.93 2.92 32.85 605.08 0.41 12.08 20.77 98.1 265 1.7 180.2 31.1 1091.1 11.1 194.59 896.51 0.34 17.03 177.56 98.4 375 1.7 255 33.3 1535.89 21.9 487.11 1048.78 0.73 26.78 460.33 98.3 505 1.7 343.4 36.9 2118.38 26.1 899.12 1219.26 2.32 63.40 835.71 97.0 565 1.7 384.2 31.6 2348.61 26 1088.55 1260.06 5.5 103.48 985.07 95.6

TABLE 5 summarizes the test data with regard to bed volumes and meq/g for columns one and two (1.7 L/min flow rate): Bed Volumes meq/g for Col. 1 meq/g for Col. 2 0 0 0 14 0.051 0 58 0.210 0.001 99 0.350 0.012 180 0.519 0.099 255 0.607 0.256 343 0.705 0.466 384 0.729 0.549

Example 2 Sodium Zeolite Absorption of High Ammonia Feed Containing Calcium, Magnesium and Potassium

Tables 6 and 7 illustrate that aqueous medium containing approximately 26.5 mg/L ammonia, 127 mg/L calcium, 36 mg/L magnesium, 31 mg/L potassium, and 8.8 mg/L sodium, can be effectively treated to remove ammonia using the apparatus and methods of the present invention. The aqueous medium was pumped up-flow through a two column system similar to the one described in Example 1. The solution was pumped at a flow rate of approximately 1.7 L/min for a total time of 435 minutes.

Tables 6 and 7 show that the concentration of ammonia in the column one effluent was approximately 20.9 mg/L and the concentration in the column two effluent was approximately 16.4 mg/L. As in Example 1, an additional column would have been useful for a more complete removal of the ammonia from the solution at that flow rate. The data also illustrates that calcium loads quickly onto the zeolite and that the majority of the sodium on the zeolite prior to flow of the solution is displaced by calcium and ammonia (see FIG. 6). Note that the concentration of sodium clearly decreases from an initial concentration of greater than 200 mg/L to a concentration of less than 50 mg/L, while the concentration of calcium increases from an initial concentration of less than 25 mg/L to a concentration of greater than 100 mg/L.

TABLE 6 Ammonia Loading onto Two Column Zeolite System - Col 1 Effluent Col. 1 Effluent Flow Bed meq fed meq meq meq meq meq NH₃ meq NH₃ meq disch meq disch meq disch Time rate Vol. NH₃ fed Ca fed Mg fed K fed Na disch. on C#1 Ca Mg K 0 1.7 151 0 0 0 0 0 0 0 0 0 0 15 1.7 151 47.9 161.9 75.9 20.2 9.4 4.0 43.9 25.5 23.2 0.65 75 1.7 151 240.96 814.7 387.8 101.1 48 72.2 168.8 392.7 301.4 13.70 135 1.7 151 433.32 1472.6 708.1 179.3 87.5 183.6 249.7 877.2 613.26 39.78 195 1.7 151 621.29 2135.6 1036.9 257.6 127.8 319.2 302.1 1428 950.45 74.70 255 1.7 151 810.72 2788.4 1348.8 335.9 167.7 502.8 307.9 2009.4 1287.65 112.83 315 1.7 151 1000.1 3431.0 1652.2 414.1 207.2 663.8 336.4 2575.5 1591.12 157.17 375 1.7 151 1198.32 4063.4 1947.3 492.4 246.2 802.9 395.4 3162 1903.02 204.13 435 1.7 151 1405.96 4695.8 2242.3 570.7 284.8 955.2 450.8 3743.4 2206.49 253.70 C#1 C #2 bed elapsed Col 1 effluent mg/L wt wt vol. time NH₃ feed Ca feed Mg feed K feed Na NH3 Ca Mg K 1729 1795 0 0 26.3 127 36 31 8.5 2.22 20 11 1 1729 1795 10.2 15 26.3 127 36 31 8.5 2.22 20 11 1 1729 1795 51 75 26.5 128 37 31 8.7 9.35 72 33 5 1729 1795 91.8 135 26.4 129 38 30 8.9 15.3 95 37 10 1729 1795 132.6 195 25.8 130 39 30 9.1 18.6 108 40 13 1729 1795 173.4 255 26 128 37 30 9.2 5.2 114 40 15 1729 1795 214.2 315 26 126 36 30 8.9 22.1 111 36 17 1729 1795 255 375 27.2 124 35 30 8.8 19.1 115 37 18 1729 1795 295.8 435 28.5 124 35 30 8.7 20.9 114 36 19 total eq 26.56 127 36.56 30.33 8.79 12.08 1.56 6.35 3.00 0.78 0.38 Ammonia Loading onto Two Column Zeolite System - Col 2 Effluent Column 2 Effluent Flow Bed meq meq meq NH₃ meq meq meq meq meq Ca meq Mg meq K Time rate Vol. Na dischar on Col 2 Ca Mg K Na on Col. 1 on Col. 1 on Col. 1 0 1.7 151 0 0 0 0 0 0 0 0 0 0 15 1.7 151 257.2 2.4 1.64 0.54 0.25 0.65 266.09 136.43 52.69 19.57 75 1.7 151 740.6 12.46 59.71 66.84 135.13 0.91 1148.61 422.03 86.41 87.39 135 1.7 151 1046.6 31.62 152.01 306.54 447.03 6.13 1734.0 595.43 94.84 139.57 195 1.7 151 1268.3 80.43 238.72 658.44 801.08 13.96 2221.83 707.63 86.41 183.91 255 1.7 151 1459.0 154.75 348.01 091.94 1146.7 27 2603.22 779.03 61.12 223.04 315 1.7 151 1618.7 251.65 412.12 1556.04 1458.6 42.65 2926.96 855.53 61.12 256.96 375 1.7 151 1756.2 355.11 447.82 2055.84 1770.5 63.52 3193.04 901.43 44.26 288.26 435 1.7 151 1871.5 474.59 480.62 586.24 2082.40 89.61 3414.78 952.43 35.83 316.96 Col 2 Effluent, mg/L Time Flow rate Bed Vol. Na NH₃ Ca Mg K Na 0 1.7 151 232 1.32 0.42 0.12 1 240 15 1.7 151 232 1.32 0.42 0.12 1 240 75 1.7 151 109 1.38 13 16 0.1 199 135 1.7 151 69 2.63 47 37 2 132 195 1.7 151 50 6.7 69 42 3 110 255 1.7 151 43 10.2 85 41 5 86 315 1.7 151 36 13.3 91 37 6 73 375 1.7 151 31 14.2 98 37 8 60 435 1.7 151 26 16.4 104 37 10 50

TABLE 7 Summary of Loading and Effluent onto Columns One and Two bed vol NH₃ Ca Mg K Na Sum Column 1 - Loading on Zeolite, meq/g 0 0.000 0.000 0.000 0.000 0.000 0.000 10 0.025 0.079 0.030 0.011 −0.143 0.003 51 0.098 0.244 0.050 0.051 −0.401 0.042 92 0.144 0.344 0.055 0.081 −0.555 0.070 133 0.175 0.409 0.050 0.106 −0.660 0.081 173 0.178 0.451 0.035 0.129 −0.747 0.046 214 0.195 0.495 0.035 0.149 −0.816 0.057 255 0.229 0.521 0.026 0.167 −0.873 0.069 296 0.261 0.551 0.021 0.183 −0.918 0.098 Column 2 - Loading on Zeolite, meq/g 0 0.000 0.000 0.000 0.000 0.000 0.000 10 0.001 0.014 0.013 0.000 −0.005 0.023 51 0.033 0.182 0.093 0.007 −0.227 0.087 92 0.085 0.318 0.093 0.019 −0.383 0.131 133 0.133 0.429 0.083 0.033 −0.531 0.147 173 0.194 0.511 0.079 0.048 −0.637 0.194 214 0.230 0.568 0.074 0.064 −0.729 0.206 255 0.249 0.616 0.074 0.078 −0.800 0.217 296 0.268 0.645 0.069 0.091 −0.860 0.213 Column 1 - Effluent, mg/L 0 2.22 20 11 1 232 10 2.22 20 11 1 232 51 9.35 72 33 5 109 92 15.3 95 37 10 69 133 18.6 108 40 13 50 173 25.2 114 40 15 43 214 22.1 111 36 17 36 255 19.1 115 37 18 31 296 20.9 114 36 19 26 Column 2 Effluent, mg/L 0 1.32 0.42 0.12 1 240 10 1.32 0.42 0.12 1 240 51 1.38 13 16 0.1 199 92 2.63 47 37 2 132 133 6.70 69 42 2 110 173 10.2 85 41 3 86 214 13.3 91 37 5 73 255 14.2 98 37 6 60 296 16.4 104 37 8 50

The data in Example 2 illustrates the utility of the present invention for absorbing ammonia from an aqueous medium, in particular absorbing ammonia from an aqueous medium having a high concentration of calcium, sodium, potassium and magnesium.

Example 3 Sodium Zeolite Absorption of Ammonia from an Aqueous Medium Having High Concentrations of Calcium, Magnesium and Potassium

The data in Example 3 was prepared in a manner similar to that shown in Example 2, except that the flow rate through the two columns was approximately 1.5 L/min and the medium was run over the columns for a total of 430 minutes. As noted in Tables 8 and 9, the ammonium concentration of column one effluent was 19.7 mg/L, while the concentration of ammonium of column two was approximately 14.7 mg/L.

Note that the slightly decreased flow rate of the aqueous medium results in a higher absorption of ammonia by the zeolite as compared to the same ammonia loading performed in Example 2. Again, as described in Example 2, a third column of zeolite is required to keep the ammonia levels below 1 mg/L over the course of the experiment.

TABLE 8 Ammonia Loading onto Two Column Zeolite System - Col 1 Effluent (low flow) Col 1 Flow Bed meq fed med feq meq fed meq meq meq disch meq NH₃ meq disch meq disch meq disch Time Rate Vol. NH₃ Ca Mg fed K fed Na NH₃ of Col 1 Ca Mg K 0 1.5 150.8 0 0 0 0 0 0 0 0 0 0 10 1.5 150.8 29.6 95.3 44.6 10.7 5.94 0.193 29.38 12.75 9.55 0.038 70 1.5 150.8 203.1 662.3 312.4 75.2 41.54 30.99 172.2 377.3 255 6.944 130 1.5 150.8 370.3 1224 580.2 141.9 77.54 110.7 259.6 845.3 522.8 23.06 190 1.5 150.8 534.2 1782 847.9 208.7 113.5 203.9 330.3 1349 798 46.07 250 1.5 150.8 698.1 2332 1123 275.5 148.8 306.8 391.4 1880 1081 75.99 310 1.5 150.8 861.4 2872 1405 342.2 182.8 437.3 424.2 2420 1363 112.8 370 1.5 150.8 1024 3407 1696 408.9 216.1 576.1 447.9 2965 1638 152 430 1.5 150.8 1187 3938 1986 475.7 248.2 702.8 483.9 3536 1921 193.4 Column 1 Effluent Col 1 Col 2 bed Elap. Feed Feed Feed Feed Feed NH₃ Ca Mg K wt wt vol Min. NH₃ mg/L Ca mg/L Mg mg/L K mg/L Na mg/L mg/L mg/L mg/L mg/L 1729 1795 0 0 27.6 127 36 28 9.1 0.18 17 7.7 0.1 1729 1795 6 10 27.6 127 36 28 9.1 0.18 17 7.7 0.1 1729 1795 42 70 27 126 36 28 9.1 4.79 81 33 3 1729 1795 78 130 26 125 36 29 9.2 12.4 104 36 7 1729 1795 114 190 25.5 124 36 29 9.2 14.5 112 37 10 1729 1795 150 250 25.5 122 37 29 9 16 118 38 13 1729 1795 186 310 25.4 120 38 29 8.7 20.3 120 38 16 1729 1795 222 370 25.3 119 39 29 8.5 21.6 121 37 17 1729 1795 258 430 25.3 118 39 29 8.2 19.7 127 38 18 Ammonia Loading onto Two Column Zeolite System - Col 2 Effluent (low flow) Col 2 meq meq meq Na NH₃ meq NH₃ meq Ca meq Mg meq K meq Na Ca on meq Mg meq K meq Na meq Ca meq Mg disch disch on col 2 disch disch disch disch Col 1 on col 1 on col 1 on col 1 on col 2 on col 2 0 0 0 0 0 0 0 0 0 0 0 0 0 148.7 0.107 0.086 1.8 0.409 0.038 167.6 82.5 35.08 10.70 −142 10.95 9.136 571.3 0.750 30.24 136.8 186.4 2.230 883.7 285 57.4 68.25 −529 240.5 68.64 841.3 7.179 103.5 438.3 461.6 4.642 1369 379.5 57.4 118.8 −763 406.9 61.20 1053 25.37 178.5 825.3 744.2 9.246 1760 433.5 49.96 162.6 −939 523.9 53.76 1217 59.38 247.4 1266 1034 16.15 2085 451.5 42.52 199.5 −999 613.9 46.32 1350 126.2 311.0 1739 1310 27.7 2371 451.5 42.52 229.4 −999 681.5 53.76 1475 201.5 374.7 2238 1585 41.47 2609 442.5 57.34 257 −999 726.5 53.76 1582 296 406.8 2796 1860 59.89 2810 402 64.84 282.3 −999 740 61.20 Col 2 Effluent Na mg/L NH₃ mg/L Ca mg/L Mg mg/L K mg/L Na mg/L 228 0.1 2.4 0.33 0.1 257 228 0.1 2.4 0.33 0.1 257 108 0.1 30 25 1 183 69 1 67 37 1 124 54 2.83 86 38 2 100 42 5.29 98 39 3 83 34 10.4 105 37 5 73 32 11.7 111 37 6 61 27.5 14.7 124 37 8 51.3

TABLE 9 Summary of Loading and Effluent in Table 8 bed vol. NH₃ Ca Mg K Na Sum Column 1 - Loading of zeolite, meq/g 0 0 0 0 0 0 0 6 0.017 0.048 0.02 0.006 −0.083 0.009 42 0.1 0.165 0.033 0.039 −0.306 0.031 78 0.15 0.219 0.033 0.069 −0.442 0.03 114 0.191 0.251 0.029 0.094 −0.543 0.022 150 0.226 0.261 0.025 0.115 −0.618 0.010 186 0.245 0.261 0.025 0.133 −0.675 −0.011 222 0.259 0.256 0.033 0.149 −0.728 −0.031 258 0.280 0.233 0.037 0.163 −0.772 −0.059 Column 2 - Loading on zeolite, meq/g 0 0 0 0 0 0 0 6 0 0.006 0.005 0 −0.011 0.001 42 0.017 0.134 0.038 0.003 −0.174 0.018 78 0.058 0.227 0.034 0.01 −0.294 0.035 114 0.099 0.292 0.03 0.021 −0.394 0.048 150 0.138 0.342 0.026 0.033 −0.484 0.055 186 0.173 0.380 0.03 0.047 −0.569 0.062 222 0.209 0.405 0.03 0.062 −0.632 0.073 258 0.227 0.412 0.034 0.074 −0.684 0.064 Column 1 - Effluent, mg/L 0 0.18 17 7.7 0.1 228 6 0.18 17 7.7 0.1 228 42 4.79 81 33 3 108 78 12.4 104 36 7 69 114 14.5 112 37 10 54 150 16 118 38 13 42 186 20.3 120 38 16 34 222 21.6 121 37 17 32 258 19.7 127 38 18 27.5 Column 2 - Effluent, mg/L 0 0.1 2.4 0.33 0.1 257 6 0.1 2.4 0.33 0.1 257 42 0.1 30 25 1 183 78 1 67 37 1 124 114 2.83 86 38 2 100 150 5.29 98 39 3 83 186 10.4 105 37 5 73 222 11.7 111 37 6 61 258 14.7 124 37 8 51.3

The data in Example 3 again illustrates the utility of the present invention. Zeolite absorbs ammonia from an aqueous medium with high affinity, even in the presence of high concentrations of calcium, magnesium, and potassium.

Example 4 Calcium Zeolite Absorption of Ammonia from an Aqueous Medium Having High Concentrations of Calcium, Magnesium and Potassium

The following Example illustrates that calcium treated zeolite provides an excellent column material for absorbing ammonia from an aqueous medium (see Table 10). One hundred grams of zeolite, 20×35 mesh, was contacted with a CaCl₂ solution (20 grams dissolved into 1,000 ml demineralized water) overnight. The CaCl₂ treated zeolite was moved to a column where fines and clays were removed and the zeolite weight determined.

A flow rate of 4 ml/min ammonia sample was passed over the zeolite column and samples of the column discharge taken every one hour (composite samples submitted for testing). A dissolved eluant containing 438 grams CaCl₂ in 2000 mls demineralized water, pH of 10 (adjusted with NaOH) was used to elute zeolite at a solution flow rate of 5 ml/min. Discharged volumes were collected using the following formula: Z3-A=0–300 ml, Z3-B=300–600 ml, Z3-C=600–900 ml, Z3-D=900–1500, Z3-E=1500–2000 ml, Z3-E=1500–2000 ml.

TABLE 10 Calcium Form Zeolite Absorption of Ammonia Analysis, mg/L Zeolite loading, meq/g NH₃ grab % ID Day Vol Ca Mg K Na NH₃ Ca Mg K Na NH₃ feed/dis Elu Z3 0 feed 97 22 34 .67 30.2 Z3 1 5010 41 .65 2.2 140 1.63 .14 .09 .04 −.3 .08 29.6/ Z3 2 4760 110 5.8 2.7 49 7.64 .11 .15 .08 −.4 .15 27.8/11.8 Z3 3 6450 90 13 3.2 16 17.2 .13 .2 .13 −.45 .186 27.8/21 Z3 4 4820 81 16 4.9 3.7 24.5 .17 .22 .17 −.45 .195 28.8/24.1 Began Elution −A 6 300 high 120 110 14 204 .19 .16 −.45 .16 /184 18 −B 6 300 high 29 110 .7 186 .19 .15 −.45 .13 /148 35 −C 6 300 high 23 96 4.3 166 .18 .14 −.46 .1 /186 50 −D 6 500 high 17 85 3.7 111 .17 .13 −.46 .065 /67 67 −E 6 500 high 13 76 3.7 67.7 .17 .12 −.46 .045 /59 77 −F 14 500 high 29 110 22 69 .16 .11 −.46 .025 /41 87 −G 14 500 high 5.7 110 61 32 .15 .09 −.47 .015 /32 92 −H 14 500 high 4.6 120 100 17 .15 .08 −.5 .01 /18 95 Second Cycle Z3 15 feed 92 26 38 45 51.7 /5.5 Z3 15 4860 180 .5 9 31 22.3 −.2 .1 .04 .03 .08 47.6/ Z3 16 6900 140 5 11 56 29 −.38 .22 .08 0 .16 41.7/32.4 Z3 17 6350 110 17 13 56 34.4 −.44 .27 .12 −.03 .19 41.3/36.6 Z3 20 9999 108 18 19 60 36 −.6 .39 .22 −.16 .25 39.1/33.8 Z3 21 1500 79 18 23 54 36.6 −.6 .4 .22 −.16 .25 37.7/33.3 Began Elution −45° C. −F 300 170 490 420 276 .36 .18 −.22 .2 20 −G 340 36 660 200 282 .35 .13 −.25 .143 42 −H 260 22 540 140 172 .34 .09 −.26 .117 53 −I 470 14 390 130 102 .33 .04 −.29 .089 64 −J 300 9 330 140 51 .33 .02 −.31 .08 68 −K 570 6.3 230 130 37 .33 −.01 −.34 .07 73 −L 580 3.1 180 120 15 .33 −.04 −.37 .062 75 −M 590 2.4 160 130 15 .33 −.07 −.40 .057 77

Table 11 illustrates a second test as above, however, the zeolite was eluted using a calcium concentration of 34.3 g/L. Sample IDs are the same as above, and assume 5 ppm NH₃ blank on strip.

TABLE 11 Calcium Form Zeolite Absorption of Ammonia NH₃ Analysis, mg/L Zeolite Loading, meq/g Feed/ NH₃ ID Day Vol Ca Mg K Na NH₃ Ca Mg K Na NH₃ Dis Elut Z5 wash 350 12000 1.6 28 40 7 .325 −.07 −.4 0.6 feed 92 37 34 54 34 0 0 0 .01 34/ 1 6050 190 2 8.2 38 7.6 −.3 .17 .04 .04 .1 33.3/ 2 6450 140 21 8 53 18.2 −.4 .26 .08 .04 .16 32.7/ 3 6400 110 29 8.9 54 28 −.5 .3 .12 .04 .18 33.4/ 4 6100 110 31 9.6 58 30.4 −.6 .33 .16 .03 .19 32.7/31 wash 200 64 19 5.8 34 23.6 −H recyl 15000 20 240 120 strip −A 4 300 9500 230 47 220 76 0.28 0.18 0.02 0.177 /95 7 −B 300 14000 590 100 200 98 0.27 0.19 0.01 0.161 /102 15 −C 300 14000 42 100 160 87 0.26 0.2 0.01 0.146 23 −D 6 500 15000 76 130 150 81 0.24 0.21 0 0.124 /80 35 −E 500 15000 39 140 130 71 0.23 0.23 0 0.1 /73 45 −F 500 15000 29 150 120 52 0.23 0.24 0 0.09 /43 52 −G 8 500 15000 37 150 120 42 0.22 0.25 0 0.08 /34 58 −I 500 15000 12 78 100 39 0.23 0.27 0 0.07 63 −J 500 14000 11 83 100 18 0.23 0.29 0.01 0.07 65 −K 960 15000 11 110 110 20 0.24 0.32 0.01 0.06 70 −L wash 300 5900 10 50 52 0.24 0.32 0.01 Second cycle Z5 feed 69 23 28 42 43.9 43.9/ 10 6150 140 3.6 15 30 16.8 −.2 .33 .34 .04 .16 45.8/ 11 6600 94 18 25 52 30.2 −.3 .36 .35 .01 .22 44.9/ 15 6150 86 20 24 48 29.2 −.4 .38 .35 −.01 .27 44.8/31 16 6150 71 23 23 51 34.3 −.4 .38 .36 −.03 .31 44.4/32 Elution recy 15000 11 120 110 strip −II 42 g/l 310 17 200 250 182 .38 .34 .26 16 −JJ CaCl₂ 410 27 190 160 171 .37 .33 .22 30 −KK 280 20 180 120 146 .37 .33 .2 37 −LL 300 18 170 110 149 .37 .32 .17 46 M 500 32 160 110 143 .36 .32 .12 59 N 500 15 140 100 119 .35 .32 .09 71 O 300 13 130 100 99 .35 .31 .22 76 P 340 13 120 100 96 .35 .31 .07 82 Q 280 13 120 100 67 .35 .31 .06 86 S 500 21 120 110 49 .35 .31 .04 90 T 500 10 140 110 49 .34 .3 .03 95 U 520 4.1 140 74 41 .34 .28 .02 99 V 505 3.6 140 64 33 .34 .26 .02 102 X 440 3.2 140 63 26 .34 .25 .003 104 Y 500 9.7 140 71 25 .33 .23 107 Z 500 2.4 130 62 17 .33 .21 108

Example 5 Sodium Zeolite Absorption of Ammonia in a Five-Column Configuration, Including Migration of Zeolite

FIGS. 7A to 7H illustrate a five-column run on a natural supply of aqueous medium located in Colorado City, Colo. The initial concentration of target materials in the aqueous medium was approximately 97 mg/L calcium, 14 mg/L magnesium, 19 mg/L potassium, 16 mg/L sodium, 29 mg/L ammonia (note that these values fluctuate slightly due to the natural source feed). The run was performed at a flow rate of approximately 1.1 L/minute for a period of approximately 24.5 hours. As can be seen in FIG. 7, the concentration of ammonia in the column 5 effluent is at all times less than 1 mg/L, indicating that the five-column configuration a the above mentioned flow rate is effective in removing ammonia from an aqueous medium to levels less than the acceptable discharge levels set by the EPA.

The zeolite was counter-current migrated throughout the course of the experiment. Note that the zeolite in column one was regenerated after day three, i.e., passed through a brine solution, and re-connected to the system after column five. The concentration of the regenerated column one effluent is lower than the column five effluent, indicating that the regenerated column one is still effective at removing even low concentrations of ammonia.

The present Example illustrates the utility of the present invention for removing ammonia from an aqueous medium-especially with regard to using a counter-current migration of zeolite.

Example 6 Sodium Zeolite Absorption of Ammonia in a Five-Column Configuration Including Migration of Zeolite

Table 12 illustrates results from a five-column run on a natural supply of aqueous medium located in Burley, Id. The initial concentration of the aqueous medium was approximately 58 mg/L calcium, 14 mg/L magnesium, 25 mg/L potassium, 12.6 mg/L ammonia and 150 mg/L sodium. As in Example 5, the values tended to fluctuate due to the natural source of the feed. The flow rate for the run was approximately 1.7 L/minute over a period of 455 minutes.

The results show that the concentration of ammonia in the column 5 effluent (discharge) was at all times less than 1 mg/L ammonia, indicating that a five-column configuration at the above mentioned flow rate was effective at removing ammonia from this particular water source.

TABLE 12 Five Column Run at Burley Idaho, Feed Elapsed Cum. Bed Cum Feed, mg/L Day Time Time Minutes Rate Vol. BV Ca Mg K NH₃ Na 1 13:50 0 0 1700 58 14 25 12.6 150 1 15:00 70 70 1700 64 64 58 14 25 12.6 150 15:55 125 125 1700 51 115 58 14 25 12.6 150 2  9:00 0 125 1700 0 115 59 14 25 14.9 145 2 10:00 60 185 1700 55 170 59 14 25 14.9 145 12:00 120 305 1700 110 280 61 14 25 14 135 14:00 120 425 1700 110 391 60 14 25 14 140 14:30 30 455 1700 28 418 60 14 25 14 140 Cum. meq fed to circuit Day Time Elapsed Time Minutes Rate Liters Ca Mg K NH₃ Na 1 13:50 0 0 1700 0 1 15:00 70 70 1700 119 345 69 76 88 776 15:55 55 125 1700 93.5 271 54 60 69 610 2  9:00 0 125 1700 0 0 0 0 0 0 2 10:00 60 185 1700 102 301 59 65 89 643 12:00 120 305 1700 204 622 118 130 168 1197 14:00 120 425 1700 204 612 118 130 168 1242 14:30 30 455 1700 51 153 29 33 42 310 1 13:50 0 0 1 15:00 70 70 15:55 55 125 2  9:00 0 125 2 10:00 60 185 12:00 120 305 14:00 120 425 14:30 30 455 1 13:50 0 0 1 15:00 70 70 15:55 55 125 2  9:00 0 125 2 10:00 60 185 12:00 120 305 14:00 120 425 14:30 30 455 Five Column Run at Burley Idaho - Col. 1 discharge, mg/L Elapsed Cum. Bed Cum Column 1 Discharge, mg/L Day Time Time Minutes Rate Vol. BV Ca Mg K NH₃ Na 1 13:50 0 0 1700 1 15:00 70 70 1700 64 64 12 12 2 1.33 240 15:55 125 125 1700 51 115 12 12 2 1.33 240 2  9:00 0 125 1700 0 115 2 10:00 60 185 1700 55 170 12:00 120 305 1700 110 280 14:00 120 425 1700 110 391 14:30 30 455 1700 28 418 Cum. meq discharging Column 1 Day Time Elapsed Time Minutes Rate Liters Ca Mg K NH₃ Na 1 13:50 0 0 1700 0 1 15:00 70 70 1700 119 71 59 6.1 9.3 1242 15:55 55 125 1700 93.5 56 46 4.8 7.3 976 2  9:00 0 125 1700 0 2 10:00 60 185 1700 102 12:00 120 305 1700 204 14:00 120 425 1700 204 14:30 30 455 1700 51 Day Time Elapsed Time Cum. Minutes Ca Mg K NH₃ Na 1 13:50 0 0 Net Loading on Column 1 1 15:00 70 70 0 0 0 0 0 15:55 55 125 274 10 70 79 −466 2  9:00 0 125 215 7.7 55 62 −366 2 10:00 60 185 12:00 120 305 14:00 120 425 14:30 30 455 1 13:50 0 0 1 15:00 70 70 Cumulative Loading on Column 1 15:55 55 125 0 0 0 0 0 2  9:00 0 125 274 10 70 79 −466 2 10:00 60 185 489 17 125 141 −832 12:00 120 305 14:00 120 425 14:30 30 455 Five Column Run at Burley Idaho - Col. 2 discharge, mg/L Elapsed Cum. Bed Cum Column 2 Discharge, mg/L Day Time Time Minutes Rate Vol. BV Ca Mg K NH₃ Na 1 13:50 0 0 1700 1 15:00 70 70 1700 64 64 <1 <2 2 0.8 290 15:55 125 125 1700 51 115 <1 <2 2 0.8 290 2  9:00 0 125 1700 0 115 2 10:00 60 185 1700 55 170 19 18 3 2.3 215 12:00 120 305 1700 110 280 40 16 7 5.8 180 14:00 120 425 1700 110 391 50 14 11 9.1 165 14:30 30 455 1700 28 418 50 14 11 9.1 165 Cum. meq discharging Column 2 Day Time Elapsed Time Minutes Rate Liters Ca Mg K NH₃ Na 1 13:50 0 0 1700 0 6 9.8 6.1 5.6 1500 1 15:00 70 70 1700 119 4.7 7.7 4.8 4.4 1179 15:55 55 125 1700 93.5 0 0 0 0 0 2  9:00 0 125 1700 0 97 76 7.8 14 953 2 10:00 60 185 1700 102 408 134 37 70 1597 12:00 120 305 1700 204 510 118 57 109 1463 14:00 120 425 1700 204 128 29 14 27 366 14:30 30 455 1700 51 Net Loading on Column 2 Day Time Elapsed Time Cum. Minutes Ca Mg K NH₃ Na 1 13:50 0 0 0 0 0 0 0 1 15:00 70 70 65 49 0 3.7 −259 15:55 55 125 51 38 0 2.9 −203 2  9:00 0 125 0 0 0 0 0 2 10:00 60 185 204 −17 57 76 −310 12:00 120 305 214 −17 94 98 −399 14:00 120 425 102 0 73 59 −222 14:30 30 455 26 0 18 15 −55 Cumulative Loading on Column 2 Day Time Elapsed Time Cum. Minutes Ca Mg K NH₃ Na 1 13:50 0 0 0 0 0 0 0 1 15:00 70 70 65 49 0 15:55 55 125 117 87 0 2  9:00 0 125 117 87 0 2 10:00 60 185 321 71 57 12:00 120 305 535 54 151 14:00 120 425 637 54 224 14:30 30 455 663 54 243 Five Column Run at Burley Idaho - Col. 3 discharge, mg/L Elapsed Cum. Bed Cum Column 3 Discharge, mg/L Day Time Time Minutes Rate Vol. BV Ca Mg K NH₃ Na 1 13:50 0 0 1700 1 15:00 70 70 1700 64 64 <1 <2 2 1.05 295 15:55 125 125 1700 51 115 <1 <2 2 1.05 295 2  9:00 0 125 1700 0 115 2 10:00 60 185 1700 55 170 1 <2 1 1.2 280 12:00 120 305 1700 110 280 13 16 2 1.7 215 14:00 120 425 1700 110 391 33 16 3 2.9 190 14:30 30 455 1700 28 418 33 16 3 2.9 190 Cum. meq discharging Column 3 Day Time Elapsed Time Minutes Rate Liters Ca Mg K NH₃ Na 1 13:50 0 0 1700 0 6 9.8 6.1 7.4 1526 1 15:00 70 70 1700 119 4.7 7.7 4.8 5.8 1199 15:55 55 125 1700 93.5 0 0 0 0 0 2  9:00 0 125 1700 0 5.1 8.4 2.6 7.2 1242 2 10:00 60 185 1700 102 133 134 10 20 1907 12:00 120 305 1700 204 337 134 16 35 1685 14:00 120 425 1700 204 84 34 3.9 8.7 421 14:30 30 455 1700 51 Net Loading on Column 3 Day Time Elapsed Time Cum. Minutes Ca Mg K NH₃ Na 1 13:50 0 0 0 0 0 0 0 1 15:00 70 70 0 0 0 −1.8 −26 15:55 55 125 0 0 0 −1.4 −20 2  9:00 0 125 0 0 0 0 0 2 10:00 60 185 92 67 5.2 6.6 −288 12:00 120 305 275 0 26 49 −310 14:00 120 425 173 −17 42 74 −222 14:30 30 455 43 −4.2 10 19 −55 Cumulative Loading on Column 3 Day Time Elapsed Time Cum. Minutes Ca Mg K NH₃ Na 1 13:50 0 0 0 0 0 0 0 1 15:00 70 70 0 0 0 −1.8 −26 15:55 55 125 0 0 0 −3.1 −46 2  9:00 0 125 0 0 0 −3.1 −46 2 10:00 60 185 92 67 5.2 3.5 −334 12:00 120 305 367 67 31 53 −645 14:00 120 425 541 50 73 127 −867 14:30 30 455 584 46 83 146 −922 Five Column Run at Burley Idaho - Col. 4 discharge, mg/L Elapsed Cum. Bed Cum Column 4 Discharge, mg/L Day Time Time Minutes Rate Vol. BV Ca Mg K NH₃ Na 1 13:50 0 0 1700 1 15:00 70 70 1700 64 64 <1 <2 2 1.01 295 15:55 125 125 1700 51 115 <1 <2 2 1.01 295 2  9:00 0 125 1700 0 115 2 10:00 60 185 1700 55 170 <1 <2 1 1.1 290 12:00 120 305 1700 110 280 2 16 1 1 235 14:00 120 425 1700 110 391 10 18 1 1.3 220 14:30 30 455 1700 28 418 10 18 1 1.3 220 Cum. meq discharging Column 4 Day Time Elapsed Time Minutes Rate Liters Ca Mg K NH₃ Na 1 13:50 0 0 1700 0 6 9.8 6.1 7.1 1526 1 15:00 70 70 1700 119 4.7 7.7 4.8 5.6 1199 15:55 55 125 1700 93.5 0 0 0 0 0 2  9:00 0 125 1700 0 5.1 8.4 2.6 6.6 1286 2 10:00 60 185 1700 102 20 134 5.2 12 2084 12:00 120 305 1700 204 102 151 5.2 16 1951 14:00 120 425 1700 204 26 38 1.3 3.9 488 14:30 30 455 1700 51 Day Time Elapsed Time Cum. Minutes Ca Mg K NH₃ Na 1 13:50 0 0 Net Loading on Column 4 1 15:00 70 70 0 0 0 0 0 15:55 55 125 0 0 0 0.3 0 2  9:00 0 125 0 0 0 0.2 0 2 10:00 60 185 0 0 0 0 −44 12:00 120 305 0 0 0 0.6 −177 14:00 120 425 112 0 5.2 8.4 −266 14:30 30 455 235 −17 10 19 −67 Cumulative Loading on Column 4 Day Time Elapsed Time Cum. Minutes Ca Mg K NH₃ Na 1 13:50 0 0 0 0 0 0 0 1 15:00 70 70 0 0 0 0.3 0 15:55 55 125 0 0 0 0.5 0 2  9:00 0 125 0 0 0 0.5 0 2 10:00 60 185 0 0 0 1.1 −44 12:00 120 305 112 0 5.2 9.5 −222 14:00 120 425 347 −17 16 29 −488 14:30 30 455 405 −21 18 34 −554 Five Column Run at Burley Idaho - Col. 5 discharge, mg/L Elapsed Cum. Bed Cum Column 4 Discharge, mg/L Day Time Time Minutes Rate Vol. BV Ca Mg K NH₃ Na 1 13:50 0 0 1700 1 15:00 70 70 1700 64 64 15:55 125 125 1700 51 115 2  9:00 0 125 1700 0 115 2 10:00 60 185 1700 155 170 2 <2 1 0.2 335 12:00 120 305 1700 1110 280 1 <2 1 0.4 285 14:00 120 425 1700 1110 391 3 18 1 0.1 225 14:30 30 455 1700 128 418 3 18 1 0.1 225 Cum. meq discharging Column 5 Day Time Elapsed Time Minutes Rate Liters Ca Mg K NH₃ Na 1 13:50 0 0 1700 0 1 15:00 70 70 1700 119 0 0 0 0 0 15:55 55 125 1700 93.5 0 0 0 0 0 2  9:00 0 125 1700 0 0 0 0 0 0 2 10:00 60 185 1700 102 10 8.4 2.6 1.2 1486 12:00 120 305 1700 204 10 17 5.2 4.8 2528 14:00 120 425 1700 204 31 151 5.2 1.2 1996 14:30 30 455 1700 51 7.7 38 1.3 0.3 499 Net Loading on Column 5 Day Time Elapsed Time Cum. Minutes Ca Mg K NH₃ Na 1 13:50 0 0 1 15:00 70 70 15:55 55 125 2  9:00 0 125 2 10:00 60 185 −5.1 0 0 5.4 −200 12:00 120 305 101 18 0 7.2 −443 14:00 120 425 71 0 0 14 −44 14:30 30 455 18 0 0 3.6 −11 Cumulative Loading on Column 5 Day Time Elapsed Time Cum. Minutes Ca Mg K NH₃ Na 1 13:50 0 0 1 15:00 70 70 15:55 55 125 2  9:00 0 125 0 0 0 0 0 2 10:00 60 185 −5.1 0 0 5.4 −200 12:00 120 305 5.1 118 0 13 −643 14:00 120 425 77 118 0 27 −687 14:30 30 455 94 118 0 31 −698

Example 7 Calcium Zeolite Absorption of Ammonia from an Aqueous Medium Containing Calcium, Magnesium, and Potassium

FIGS. 8A–F provide tabular and graphical results of a five-column test run on a feed solution containing approximately 3.5 mg/L calcium, 2 mg/L magnesium, 30 mg/L potassium, 36 mg/L ammonia and 13 mg/L sodium. The run was performed at a flow rate of 0.95 L/minute for a time period of 280 minutes. FIG. 8 shows that the concentration of ammonia in column 5 effluent began at 0.03 mg/L and finished at 2.2 mg/L. The data indicates that the five-column configuration at the above-mentioned flow rate is effective to remove ammonia to a discharge level of less than 1 mg/L. FIGS. 8A–8F illustrate the MEQ per gram loading of the various components of the feed on each column versus bed volume. Again, this graphical data shows that the calcium on the zeolite is replaced by ammonia during the absorption process.

FIGS. 9A–9F, represent the results of a continuation of the run shown above in this Example (FIGS. 8A–F) in which column one was eluted with a calcium chloride brine solution and placed back into the test after column five. The data indicates that the concentration of ammonia in the regenerated column one effluent is at all times, but for the final reading, at a concentration of less than 1 mg/L. The final concentration of ammonia in the column one effluent was 1.5 mg/L, suggesting that the absorption of ammonia can be accomplished in a batch or a continuous process.

Finally, FIGS. 10A–F represents tabular and graphical results of a continuation of the above data in which the second column was regenerated and migrated and the concentration of potassium in the feed solution was increased from approximately 30 mg/L initially to approximately 90 mg/L. These results show that the transfer of potassium through zeolite to the brine does not substantially effect the absorption of ammonia.

Example 8 Industrial Scale-Up for Ammonia Removal and Destruction at a Theoretical Treatment Facility

The following Table 13 provides a potential scale-up calculation for removing and destroying ammonia from a hypothetical one million gallon a day treatment facility. The amount of zeolite material and the size of the tank(s) for commercial applications are selected based on a number of design parameters, including but not limited to, average amount of ammonia in the water, desired levels of reduction, plant capacity (1 MGD) and the types of zeolites used.

Predictable scale-up for the methods according to the present invention are shown below with respect to a theoretical one million gallon per day treatment facility.

Table 13 summarizes a typical scale-up calculation for design of an industrial capacity system (1 MGD). A 98% reduction in ammonia concentration at the facility is attainable by using approximately 125 tons of zeolite. Each absorption column should be approximately 9 feet in diameter and 25 feet tall. A maximum rate of migration of the zeolite is approximately 116 pounds per minute and a minimum rate is 58 pounds per minute. Ultimately, the system provides for the destruction of approximately 1,673 pounds of ammonium sulfate solution per day.

TABLE 13 Material Balance For Calcium, Sulphuric acid and Ammonia At a 1 MGD Facility Value Input Data Gallons per day 1.008 million Gallons per minute 700 Ammonia in feed (mg/L) 40 Assumptions # lime/# NH₃ for stripping 1.64 zeolite # lime/# NH₃ for stripping 0.82 brine # lime/# NH₃ for 1.55 destruction # H₂SO₄/# NH₃ for ammonia 2.875 removal CaSO₄ produced/# of NH₃ 5.1 Results 1000 gallons/day 1,008 Pounds per day ammonia 334.7 Pounds zeolite loaded/day 83,664 Pounds zeolite stripped/min 58 Tons Zeolite in plant/3 days 125 # H₂SO₄ to remove 962 ammonia/day # (NH₄)SO₄/day 1,297 # lime for stripping zeolite 549 # lime for stripping brine 274 # lime for destruction 519 # total lime/day 1,342 Absorption Flow rate gpm/ft³ 10 Square feet needed 70 Diameter of tank 9.44 Height of tank 25 Depth of zeolite/tank 13 Cubic feet zeolite/tank 875 Pounds zeolite/tank 48,125 Tons zeolite/tank 24 Number of loading tank 4 Tons zeolite in absorption 96.25 circuit Zeolite maximum 116 pounds/min advancement rate Zeolite minimum 58 pounds/min advancement rate Desorption Retainage time (minimum) 2 hours Cubic feet advancement of 2.1 zeolite/min Pounds capacity 13,944 Tons capacity 7 Cubic feet zeolite capacity 254 Depth of zeolite 15 Square feet of base 16.9 Diameter of base 4.6 Brine flow rate/ft³ 6 Gallons per minute brine 101.4 Cubic feet of brine/minute 13.6 Minimum bed volumes 770 Ammonia Stripping Flow rate to ammonia 101.4 stripper Square feet of stripper 101.4 Diameter of stripper 11.4 Height of stripper 20 Air flow of stripper 40,673 ft³ Lime to stripper 0.93 lb/minute Ammonia Recovery Diameter of absorber 11.4 Flow rate of absorber 507 Air flow to absorber 40,673 ft³ H₂SO₄ to absorber 0.67 lb/minute Pounds (NH₄)₂SO₄ 0.90 lb/minute produced/minute Zeolite Rinse Retainage time (minimum) 0.5 hours Cubic feet advancement of 2.1 zeolite/minute Pounds capacity 3,486 Tons capacity 1.7 Cubic feet zeolite capacity 63 Depth of zeolite 15 Square feet of base 4.2 Diameter of base 2.3 Brine flow rate/ft³ 6 Gallons per minute rinse 25.4 solution Cubic feet of brine/minute 3.4 Minimum bed volumes 48 Ammonia Destruction Bleed stream to destruction 1,673.28 lbs/day stripper Cubic feet liquid to 26.82 ft³/day destruction stripper Liquid to stripper/minute 0.139 gallons/minute Air to destruction 55.865 ft³/min stripper/minute Gypsum production 1706.7456/day Number/minute gypsum 1.19 production

The above discussed scale-up calculation illustrates the utility of the present invention, for large scale application of the present invention.

Example 9 Pilot Plant Study—Ammonia Removal Pilot Plant at Tomahawk Wastewater Treatment Facility, Johnson County, Kansas.

The Tomahawk wastewater treatment facility has a trickling filter system with ammonia discharges that limit the plant throughput. The plant has a current capacity of 9 MGD, but operates at 4 MGD and has an ammonia permit of 4 mg/L.

A six day pilot study was conducted to verify the applicability of the methods and apparatuses of the present invention at removing ammonia from a wastewater source. The pilot study was set-up to test 3.5 gallons/minute, having a feed concentration of 11.65 mg/L ammonia. A total of 29,000 gallons of water was treated during the study. Sampling and analysis were conducted on-site using a Hanna Ion Specific Meter for ammonia and analysis was re-checked at the Johnson County Wastewater Lab (note that discrepancies between lab results appear to be due to the differences in the sample analysis temperature).

As shown in Table 14, the pilot ammonia removal plant was effective at removing a sub-permit level of ammonia. Ultimately, ammonia discharge was lowered to 1.14 mg/L, showing an ammonia recovery of 90.2%. The chemical consumption used during the test was below expectation.

TABLE 14 Johnson County Pilot Plant JCW Lab WRT JCW Lab WRT feed discharge discharge feed NH₃—N NH₃—N NH₃—N NH₃—N Day Time mg/L mg/L mg/L mg/L 1 12 PM  10.52 12.80 0.17 0.95 1 2 PM 12.20 15.40 0.10 1.12 1 3 PM 10.06 10.60 0.56 1.14 4 7 PM 11.24 9.12 0.29 0.70 5 8 AM 8.84 8.78 0.98 1.43 Average: 10.57 11.34 0.39 1.07

The data in the pilot study shows the utility of the present invention at removing ammonia from a waste water stream.

Example 10 Pilot Plant Study-Ammonia Removal Pilot Plant at Colorado City Wastewater Treatment Facility, Colo. City, Colo.

The Colorado City wastewater treatment facility has an aerated lagoon system with ammonia discharges that limit the plant throughput. The plant has a current capacity of about 0.35 MGD and an ammonia permit level of 10 mg/L, which is expected to be decreased to 2 mg/L in the near future.

A six day pilot study was conducted to verify the applicability of the methods and apparatuses of the present invention at removing ammonia from a wastewater source. The pilot study was set-up to test 15 gallons/minute, having a feed concentration of 16.2 mg/L ammonia. A total of 65,300 gallons of water was treated during the study. Sampling and analysis were conducted on-site using a Hanna Ion Specific Meter for ammonia.

As shown in FIG. 11, the pilot ammonia removal plant was effective at removing a sub-permit level of ammonia. Ultimately, ammonia discharge was lowered to 0.6 mg/L, showing an ammonia recovery of 96.5%. The chemical consumption used during the test was at or below expectation.

Example 11 Pilot Plant Study-Air Stripping Ammonia from Feed Having High Ammonia Levels

The pilot study was performed for the City of Harrisburg in an effort to remove ammonia directly to an air stripping unit from a high ammonia waste stream (the secondary digester discharge). The basic process consist of first clarifying the feed medium from the secondary digester and filter press returning solids to the filter press for removal from the system and air stripping the ammonia from the medium. The ammonia is then recaptured in a mild acid solution to form up to 20% ammonium sulfate. The low ammonia feed medium is then returned to the process plant. The ammonium sulfate can be used as fertilizer or burned to release nitrogen as has been discussed above.

Note that it was originally hoped that the secondary digester discharge could be handled with no additional clarification but the discharge was too viscous, having to many large particles of plastic and other waste. As such, it was necessary to clarify the solution prior to air stripping.

The schematic diagram in FIG. 12 provides an overview of the steps performed in the process. For example, feed 500 is filtered 502 and/or clarified 504 to provide a high ammonia stream 506 for the air stripping process. The filtrate cycles through an ammonia stripper 508 and scrubber 510 as previously described, to provide an ammonium sulfate solution for storage in a tank 512. Acid 514 and caustic 516 storage tanks are shown. The data, as illustrated in Table 15, shows that ammonia recoveries of about 90 to 98% could be achieved when the pH was maintained at about 10. Caustic consumption was lower than expected, averaging 3.68 pounds per 1000 gallons treated. Recovery is directly related to the pH of the solution, where a pH of 10 to 12 is necessary to have recovery over 90%. The average results of the four day test were: feed rate=0.52 gallons/min., feed concentration=274 mg/L ammonia, discharge pH=10, the discharge ammonia concentration=21 mg/L, providing a recovery of 93% on average.

TABLE 15 Ammonia Recover From A Highly Concentrated Ammonia Source Feed Feed Feed Feed pH Day Time Temp Flow Total Target/Actual Feed NH₄ 1 start 0.53 216.7 10.5/10.2 181 20 min 0.57 224 10.5/11 212 42 235.8 56 0.51 243.1 10.5/10.2 196 80 0.54 256.5 10.5/10.2 110 0.45 271.9 10.2/10.8 193/217 140 0.48 287.2 10/11 192 170 0.51 301.4 10/10 188 200 27.4° C. 0.56 316.4 10/10.1 99 230 0.47 330.5 10.0/9.7 180.5 290 0.53 356 9/9.3 609 320 0.55 377.7 9/8.7 350 27.5° C. 0.61 391.3 9/8.9 210 380 0.61 410.2 9/9.8 410 0.53 426.2 9.8/10 209.5 440 27.6° C. 0.5 442.5 9.5/10.6 455 288.5 470 0.51 458.3 9.5/9.8 500 0.5 473.2 9.2/9.8 530 0.49 484.2 9.2/10.9 2 start 20 0.50 503.1 9.4 50 0.51 517.4 9.1 236 80 26.0° C. 0.50 531.8 9.9 110 0.48 546.6 9.7 213 140 0.49 561.5 10 170 0.54 577.4 9.7 212 200 0.55 592.3 9.5 211 230 0.54 607.2 9.9 214 3 start 619.2 15 30.2° C. 0.52 627.5 9.9 283 45 0.52 643.4 10.2 270 75 0.52 658.5 10.3 278 105 0.55 674.6 11 251 135 0.53 689.8 10.7 266 165 0.43 702.6 9.9 295 3 re-start 0.48 713 9.5 36 28.8° C. 0.50 821.9 11.2 301 66 0.53 840.3 10 395 90 0.55 852.4 10.3 353 120 0.53 868.4 11.1 150 0.54 884.2 10.4 311 4 start 10 25.3° C. 0.5 892.2 9.9 40 0.52 905.9 10.2 573 70 0.49 921.2 10.1 391 100 0.57 937.6 10.8 307 130 0.52 954.4 10.4 307 160 0.53/ 0.51 968.5 10.2 293 190 0.51 984.8 10.2 300 220 0.49 999.6 10.3 301 250 0.50 1014.9 10.9 299 280 0.47 1029 10.4 295 310 0.5 1043.7 10.7 316 330 340 0.5 1058.6 10.4 316 370 0.5 1073.6 10.9 298 Dis- Dis- Caustic charge charge Concen. Conc. Conc. Day Time added pH NH₄ flow pH NH₄ 1 start 10.3 7.82 1.24 0.167% 20 min 10.5 15.58 1.26 0.189 42 75/75 10.6 56 120/195 10.4 6.6 1.27 1.6 0.217 80 195/390 10.9 1.27 1.7 110 185/575 10.9 3.06 1.28 1.8 0.255 140 205/780 10.1 3.55 1.27 1.9 170 155/935 10.1 8.20 1.27 2 0.323 200 175/1110 10.2 13.8 1.27 2.2 230 160/1270 10.6 3.86 1.28 2.5 290 245/1515 9.7 43.54 1.28 3.3 0.42 320 165/1680 9.2 1.29 3.1 350 125/1805 9.7 35.94 1.28 3.6 0.477 380 135/1940 9.3 1.28 3.4 410 145/2085 9.4 35.68 1.28 3.3 0.519 440 160/2245 9.8 1.28 4.2 455 9.5 29.2 470 170/2415 10.1 1.28 3.4 500 135/2550 10.0 1.28 3.7 530 125/2675 9.8 1.28 3.2 2 start 20 60/60 9.5 1.16 3.1 50 125/185 9.9 10.7 1.21 5.0 1962 80 135/320 10 1.20 3.5 110 135/455 9.9 5.08 1.20 3.8 6794 140 125/580 10 1.20 5.0 170 270/850 9.7 92 1.21 3.0 7534 200 210/1060 9.4 24 1.21 4.2 230 240/1300 9.9 25 3.2 3 start 15 150/150 9.4 53.8 1.26 3.2 45 230/380 9.8 29.1 1.27 3.4 75 270/650 9.9 26.3 1.28 3.5 105 230/880 10 28.8 1.30 3.5 135 300/1180 10.3 15.3 1.28 4.6 165 295/1475 10.5 22.9 1.27 4 3 re-start 200/1675 10.1 1.24 3.8 36 570/2245 10.2 16.7 1.24 3.9 66 330/2575 10 15.5 1.25 3.5 90 230/2805 10.2 16.1 1.25 3.7 120 270/3075 10.1 1.26 3.6 150 360/3435 10 21 1.27 3.7 4 start 10 80/80 9.9 1.21 2.6 40 260/340 10.2 25.3 1.22 3.9 70 360/700 10.2 20.1 1.23 3.5 100 300/1000 10.2 26.8 1.23 3.6 130 340/1340 10.3 18.9 1.23 4.2 160 310/1650 10.3 18.3 1.23 3.9 190 360/2010 10.3 15.3 1.24 3.9 220 270/2280 10.2 11.8 1.22 3.8 250 350/2630 10.3 11.5 1.24 3.8 280 265/2895 10.3 8.8 1.23 3.8 310 295/3190 10.3 11.7 1.23 4.1 330 340 370/3560 10.3 12.6 1.23 3.5 370 320/3880 10.3 11.2 1.23 4.3 Acid NaOH Day Time Added Air Flow ml H₂SO₄ 1 start 0.15/1528 20 min 0.145/1502 42 0.15/1528 56 0.14/1476 80 0.145/1502 110 0.135/1450 140 0.135/1450 170 50/50 0.14/1476 200 0.12/1371 230 0.14/1476 290 0.13/1424 320 90/140 0.12/1371 835 410 350 85/225 0.11/1319 710 325 380 98/323 0.12/1371 575 227 410 97/420 0.12/1371 430/1000 130/500 440 100/520 0.13/1424 840 400 455 470 105/625 0.12/1371 670 295 500 70/695 0.125/1397 535 225 530 115/810 0.11 410 110 2 start 20 0.155/1555 940 485 50 0.135/1450 815 445 80 185 0.135/1450 680 315 110 90/275 0.135/1450 545 225 140 95/365 0.135/1450 420 405 170 75/440 0.135/1450 150 330 200 75/515 0.135/1450 790 255 230 125/640 550 130 3 start 15 15/15 0.26/1420 850 485 45 130/145 0.16/1581 620 355 75 130/275 0.16/1581 350 225 105 110/385 0.155/1555 770 390 135 140/525 0.16/1581 470 250 165 285/690 0.155/1555 175  85 3 re-start 80/770 800 420 36 210/980 0.07/1060 230 210 66 160/1140 0.26 660 340 90 100/1240 0.16/1581 430 240 120 110/1350 0.16/1581 730 390 150 170/1520 0.16/1581 370 220 4 start 10 5/5 0.17/1634 920 495 40 5/10 0.16/1581 660 490 70 165/175 0.16/1581 300 325 100 155/330 0.155/1555 700 170 130 155/485 0.15 360 345 160 120/605 0.15 690 225/500 190 120/725 0.15/1555 330 345 220 125/850 0.15/1555 730 220 250 150/1000 0.15/1555 380 370 280 130/1130 0.15 735 240/500 310 95/1225 0.145/1502 440 405 330 180/1000 340 145/1370 0.14/1502 890 260 370 165/1535 0.14 570 95

The data in this Example shows that ammonia can be recovered directly from a secondary or high ammonia source. Caustic consumption for pH control was less than anticipated.

It should be understood for purposes of this disclosure, that various changes and modifications may be made to the invention that are well within the scope of the invention. Numerous other changes may be made which will readily suggest themselves to those skilled in the art and which are encompassed in the spirit of the invention disclosed herein and as defined in the appended claims. 

1. A system for removing ammonia from an aqueous medium comprising: an ammonia absorption unit for contacting an amount of zeolite with the aqueous medium; an ammonia elution unit for eluting the ammonia from the zeolite with a brine solution; an air stripping unit for dissociating the ammonia from the brine solution and providing an ammonia gas; an acid wash unit for treating the ammonia gas with an acid wash and forming an ammonium salt; a second air stripping unit for receiving the ammonium salt and a base to dissociate the ammonia in the form of ammonium hydroxide and providing an ammonia gas; and a combustion unit for receiving the ammonium gas to be burned at a controlled temperature.
 2. The system of claim 1 further comprising: a pre-burner unit for providing an exhaust gas to the ammonia gas in the combustion unit, wherein the exhaust gas raises the temperature within the combustion unit to a level appropriate for the combustion of the ammonia gas.
 3. The system of claim 1 further comprising: a re-circulation unit for concentrating the ammonium salt, the re-circulation unit providing the ammonium salt solution back to the air stripping unit for additional ammonium salt production.
 4. The system of claim 1 further comprising: a zeolite regeneration unit for regenerating fresh-zeolite from spent zeolite and providing the regenerated zeolite for continued use in the absorption unit. 